Cetus constellation
Cetus (the Whale (Sea Monster)) is a constellation on the celestial equator, best seen in the evening in December. Its brightest star is Diphda (magnitude 2.04). Cetus covers 1,231 square degrees and is the 4th-largest of the 88 constellations.
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Detailed star map of Cetus
Facts
| Latin name | Cetus (genitive: Ceti) |
|---|---|
| Abbreviation | Cet |
| Meaning | the Whale (Sea Monster) |
| Area | 1,231 square degrees (4th of 88) |
| Location | right ascension 1.7 h, declination −8° |
| Visible from | latitudes 65° N to 79° S (whole constellation) |
| Best month | December (at about 9 pm) |
| Brightest star | Diphda |
| Stars brighter than magnitude 6 | 110 |
| Named stars (IAU) | 5 |
| Messier objects | M77 |
| Neighbors | Aquarius, Aries, Eridanus, Fornax, Pisces, Sculptor, Taurus |
How to find Cetus
From 40° N (the USA, southern Europe, Japan) look south in December evenings: at about 9 pm Cetus stands highest, around 42° above the southern horizon. From 35° S (Australia, South Africa, Argentina) it is highest in the north, about 63° above the horizon. The months before and after (November and January) are also good: then it is up a couple of hours earlier or later.
Cetus borders Aquarius, Aries, Eridanus, Fornax, Pisces, Sculptor and Taurus.
Stars of Cetus
Cetus has 110 stars brighter than magnitude 6, the limit of the naked eye under a dark sky. These are the brightest:
| Star | Designation | Magnitude | Type | Distance |
|---|---|---|---|---|
| Diphda | β Ceti | 2.04 | G9.5IIICH-1 | — |
| Menkar | α Ceti | 2.53 | M1.5IIIa | 249 ly |
| Mira | ο Ceti | 3.04 | M7IIIe+Bep | 300 ly |
| — | η Ceti | 3.45 | K1.5IIICN1Fe0.5 | — |
| Kaffaljidhma | γ Ceti | 3.47 | A3V | — |
| — | τ Ceti | 3.5 | G8V | — |
| — | ι Ceti | 3.56 | K1.5III | — |
| — | θ Ceti | 3.6 | K0III-IIIb | — |
| Baten Kaitos | ζ Ceti | 3.73 | K0IIIBa0.1 | 253 ly |
| — | υ Ceti | 4.0 | M0III | — |
| — | δ Ceti | 4.07 | B2IV | — |
| — | π Ceti | 4.25 | B7V | — |
Deep-sky objects in Cetus
Cetus contains one object from Charles Messier's catalog:
- Messier 77 (M77): spiral galaxy, 8.9 mag
Printable Cetus map and outline
A black and white version for printing and a plain outline of the Cetus figure, useful for school projects, worksheets and learning to recognize the shape.
History
Cetus is one of the 48 constellations listed by Ptolemy in the Almagest (2nd century AD). Its official boundary was drawn by Eugène Delporte for the International Astronomical Union in 1930.
Questions about Cetus
What is the brightest star in Cetus?
Diphda, at magnitude 2.04.
When can you see Cetus?
Cetus is best seen in the evening in December. The whole constellation is visible from latitudes between 65° N and 79° S.
How many stars are in Cetus?
110 stars in Cetus are brighter than magnitude 6 and can be seen with the naked eye under a dark sky; 5 of them have official IAU names.
What does Cetus mean?
Cetus means “the Whale (Sea Monster)” in Latin. Its abbreviation is Cet and the genitive, used in star names such as β Ceti, is Ceti.
